JPS647103B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic polyester composition that has good moldability and can provide molded articles with excellent mechanical properties. Thermoplastic polyesters composed of aromatic dicarboxylic acids and aliphatic or alicyclic diols are widely used as fibers and films, but polyethylene terephthalate in particular has excellent properties and is used as a molding material for injection molding. Currently, it is not widely applied.
This is because polyethylene terephthalate has a particularly slow crystallization rate compared to other crystalline polymers, and does not give a satisfactory molded product under normal injection molding conditions.
This is because a molded product obtained using a mold at 110°C has non-uniform surface and internal transparency and mechanical properties. Therefore, injection molding of polyethylene terephthalate requires a mold temperature of at least 110° C. or higher, and the molding cycle becomes longer as a result, resulting in significantly lower working efficiency. Conventionally, various crystallization accelerators and crystallization nucleating agents have been studied to improve the moldability of polyethylene terephthalate, and the use of these in combination has been proposed, but it has not been possible to use a low mold temperature. too,
Both methods have advantages and disadvantages, such as not being able to shorten the molding cycle, or having to sacrifice the appearance of the molded product even if the molding cycle can be shortened, and the reality is that further improvements are desired. To improve the crystallization properties of thermoplastic polyester, it is necessary to satisfy both the heating crystallization temperature and cooling crystallization temperature, and if the heating crystallization temperature is lowered, a relatively low temperature mold can be used. It is known that the molding cycle can be shortened by increasing the crystallization temperature. However, conventional means for improving formability often do not satisfy both the temperature-raising crystallization temperature and the cooling-down crystallization temperature, and even if they do, they almost always sacrifice other properties of polyester. Where was it hot? Therefore, the present inventors investigated the possibility of molding thermoplastic polyesters such as polyethylene terephthalate using normal low-temperature molds and in a shortened molding cycle. It has been found that blending an olefinic copolymer consisting of glycidyl ester of a β-unsaturated acid has an effective effect on lowering the crystallization temperature of thermoplastic polyester. It is already known that properties such as impact resistance of polyester can be improved by blending a relatively high proportion of the above olefin copolymer into a thermoplastic polyester. It is a new finding that it acts as a crystallization accelerator that lowers the crystallization temperature of polyester when added in a certain proportion. Moreover, when the above olefin copolymer is used as a crystallization accelerator for polyester, unlike other liquid crystallization accelerators, it does not seep onto the surface of the molded product and deteriorate the appearance, and in addition, the polyester itself The advantage is that the mechanical properties of the material can be improved. However, although thermoplastic polyester compositions containing only the above-mentioned olefin copolymer have a lower heating-up crystallization temperature and can be molded at a relatively low mold temperature, on the other hand, the molding cycle cannot be shortened. Can not. The present inventors have further investigated ways to shorten the molding cycle of compositions made of thermoplastic polyester and olefin copolymer, and have found that when a specific compound is used in combination, the properties of the polyester itself are not impaired in any way. The inventors have discovered that the cooling crystallization temperature of the above composition can be increased and the molding cycle can be effectively shortened, and the present invention has been achieved. That is, the present invention uses 0.5 to 30 parts by weight of an olefin copolymer consisting of an α-olefin and a glycidyl ester of an α,β-unsaturated acid, sodium stearate, barium stearate, and epoxy stearin to 100 parts by weight of a thermoplastic polyester. sodium acid, barium epoxy stearate,
Sodium monomethyl terephthalate, sodium monomethyl isophthalate and ethylene-α, β
- Provides a thermoplastic polyester composition for molding, which contains 0.1 to 5 parts by weight of at least one compound selected from the group consisting of sodium salts of unsaturated acid copolymers. The thermoplastic polyester used in the present invention consists of a dicarboxylic acid component in which at least 40 mol% of the dicarboxylic acid component is terephthalic acid, and a diol component, and dicarboxylic acid components other than the above-mentioned terephthalic acid include azelaic acid, sebacic acid, adipic acid, Aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as dodecanedicarboxylic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl-
4,4'-dicarboxylic acid, diphenylethane-4,
Examples include aromatic dicarboxylic acids such as 4'-dicarboxylic acid or alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, singly or in mixtures, and the diol components include aliphatic glycols having 2 to 20 carbon atoms, such as ethylene glycol and propylene glycol. , 1,4-butanediol, neopentyl glycol, 1,5-pentanediol,
1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, etc., or long chain glycols with a molecular weight of 400 to 6000, such as polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, etc., and their such as mixtures. Specific examples of thermoplastic polyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexane dimethylene terephthalate, and the like. Particularly preferred among these is polyethylene terephthalate, which has good mechanical properties. In addition, the above thermoplastic polyester preferably has a relative viscosity in the range of 1.2 to 2.0, particularly 1.3 to 1.8, as measured in a 0.5% orthochlorophenol solution at 25°C. If it exceeds 2.0, a molded product with good surface gloss cannot be obtained, which is not preferable. Note that these thermoplastic polyesters are approximately 10 to 60
It can be applied even if it contains a fibrous reinforcing agent such as glass fiber or asbestos in an amount of % by weight, and in that case, the molded product can be expected to have even higher mechanical properties. The α-olefin in the olefin copolymer consisting of α-olefin and glycidyl ester of α,β-unsaturated acid used in the present invention includes ethylene, propylene, butene-1, etc., but ethylene is preferably used. . In addition, glycidyl ester of α,β-unsaturated acid has the general formula (In the formula, R is a hydrogen atom or a lower alkyl group.) Specific examples include glycidyl acrylate, glycidyl methacrylate, and glycidyl ethacrylate, with glycidyl methacrylate being preferably used. . The amount of copolymerized glycidyl ester of α,β-unsaturated acid is suitably in the range of 1 to 50% by weight. In addition, unsaturated monomers that can be copolymerized with the above copolymers at 40% by weight or less, such as vinyl ethers, vinyl esters such as vinyl acetate and vinyl propionate, acrylic acids and methacrylic acids such as methyl, ethyl, and propyl. Acid esters, acrylonitrile, styrene, etc. may be copolymerized. The appropriate amount of the above olefin copolymer is 0.5 to 30 parts by weight, especially 3 to 15 parts by weight, based on 100 parts by weight of the thermoplastic polyester; if it is less than 0.5 parts by weight, it will be difficult to use a low-temperature mold. However, if it exceeds 30 parts by weight, it becomes difficult to shorten the molding cycle and the elastic modulus of the molded product decreases, which is not preferable. The compounds used in the present invention to shorten the molding cycle of thermoplastic polyester include sodium or barium salts of stearic acid or epoxystearic acid, monomethyl monosodium terephthalate, monomethyl monosodium isophthalate, and ethylene-α,β-unsaturated It is at least one selected from the sodium salts of saturated acid copolymers, and only when these compounds are used in combination with the above olefin copolymers, a specific moldability improvement effect can be obtained. Even if neutral viscosity compounds known as crystallization nucleating agents, oxides of group metals of the periodic table, sulfates, and metal stearates other than those of the present invention are used, the above olefin copolymer It is difficult to shorten the molding cycle of thermoplastic polyester compositions that involve coalescence. The crystal nucleating agent described above, regardless of its manufacturing method,
It may contain some raw materials and by-products. In the present invention, epoxy stearate is 9,10-
Refers to sodium or barium epoxy stearate. In addition, the sodium salt of ethylene-α,β-unsaturated acid copolymer has the general formula (R is a hydrogen atom or a lower alkyl group), specifically a copolymer containing 5 to 30 mol% of acrylic acid, methacrylic acid, etc., and the α,β-unsaturated acid component is substituted with sodium. The percentage is 10 to 100%. This copolymer also contains a small proportion of other copolymerizable unsaturated monomers, such as vinyl ethers, vinyl esters such as vinyl acetate and vinyl propionate, and esters of acrylic acid and methacrylic acid. It may be something. The compounding amount of these compounds is 0.1 to 5 parts by weight, especially 0.3 to 5 parts by weight, per 100 parts by weight of thermoplastic polyester.
If the amount is 3 parts by weight or less, the molding cycle cannot be shortened, and if it is more than 5 parts by weight, the mechanical properties, particularly the impact resistance, of the molded product obtained from the composition will deteriorate, which is not preferable. Although there are no particular limitations on the means for preparing the composition of the present invention, a preferred method includes a method in which a mixture of a thermoplastic polyester, an olefin copolymer, and the above-mentioned compounds is melt-kneaded in an extruder and then cut into pellets. It should be noted that antioxidants and heat stabilizers (for example, "Irganox 1010, 1076, manufactured by Ciba Geigy,
1093'', hydroquinone, phosphites, substituted products thereof, and combinations thereof), ultraviolet absorbers (such as various resorcinols, salicylates, benzotriazoles, benzophenones, etc.), lubricants and mold release agents ( montanic acid and its salts, esters, half esters, stearyl alcohol, stearamide, etc.), dyes (e.g. nitrosine) and pigments (e.g. cadmium sulfide, phthalocyanine, carbon black, etc.); flame retardants (e.g. decabromodiphenyl); ether, halogen-based such as brominated polycarbonate, melamine or cyanuric acid-based, phosphorus-based, etc.), flame retardant aids (e.g. antimony oxide, etc.), antistatic agents (e.g. dodecylbenzenesulfonic acid, polyalkylene glycol, etc.), crystals. One or more conventional additives such as oxidation accelerators may also be added. Small amounts of other thermoplastic resins (e.g. polyethylene, polypropylene, acrylic resins, fluororesins, polyamides, polyacetals, polycarbonates, polysulfones, nylene oxide, etc.), thermosetting resins (e.g. phenolic resin,
Melamine resin, polyester resin, silicone resin, epoxy resin, etc.), soft thermoplastic resin (for example, ethylene/vinyl acetate copolymer, polyester elastomer, ethylene/propylene terpolymer, etc.) may be added. These resins may be used alone or in combination of two or more. The resin composition of the present invention can be easily molded by conventional methods such as injection molding and extrusion molding, and the resulting molded product exhibits excellent properties. The present invention will be explained below with reference to Examples. Example 1 Polyethylene terephthalate with a relative viscosity of 1.35
100 parts by weight of ethylene-glycidyl methacrylate (90/10 weight ratio) copolymer and crystal nucleating agent were mixed and blended as shown in Table 1, and melt-mixed again using a screw extruder set at 275°C. Pelletized. The crystallization temperature of the thus obtained composition was measured using a differential calorimeter model DSC-1 manufactured by PerkinElmer, and the magnitude of the crystallization rate was evaluated. Measurement method: Place the sample in a differential calorimeter and
The exothermic peak occurs when the temperature is raised at a rate of 20°C/min, and the exothermic peak occurs when the crystallization temperature is increased at a cooling rate of 20°C/min after melting at 300°C for 10 minutes in a nitrogen stream. was taken as the cooling crystallization temperature.
A high crystallization temperature and a sharp exotherm curve indicate a fast crystallization rate. The relative viscosity was measured at 25°C using an orthochlorophenol solution with a polymer concentration of 0.5%. Only the compositions according to the invention show good crystallization properties.

【table】

[Table] Example 2 Polyethylene terephthalate (relative viscosity 1.35), glass fiber (3 mm long chopped strand), and ethylene shown in Table 2 were prepared in the same manner as in Example 1.
A composition consisting of a glycidyl methacrylate copolymer (90/10 weight ratio) and various crystal nucleating agents was melt-blended and subjected to thermal analysis. In addition, the above composition was molded using a 5-ounce injection molding machine.
A No. 1 dumbbell for tensile testing as specified in ASTM D638 and an impact test piece as specified in ASTM D256 were injection molded. The injection temperature was 280°C, the injection pressure was 400Kg/cm ² , the injection and pressure holding time was 10 seconds, and the cooling time was 40 seconds, and molding was performed at mold temperatures of 80°C, 110°C, and 150°C. If a white, opaque, and uniform molded product can be obtained, mark it with an 〇; if only a molded product with uneven surfaces and insides can be obtained, mark it with an ×.
Shown in the table. In addition, in the case where a white, opaque, uniform molded product was obtained, the minimum molding time (total injection and holding time + cooling time) required to obtain a satisfactory molded product was measured. The composition of the present invention not only provides a uniform white and opaque molded product at any mold temperature, but also shortens the molding time at each temperature. Furthermore, when only ethylene-glycidyl methacrylate copolymer was used, uniform white and opaque molded products could be obtained even with a mold at 110°C, but the molding time was long, and A mold cannot produce a satisfactory molded product. Furthermore, when a nucleating agent other than that of the present invention is used, a satisfactory molded product can be obtained at low temperatures, but the molding time is long.

【table】

Claims (1)

[Claims] 1 α for 100 parts by weight of thermoplastic polyester
-0.5 to 30 parts by weight of an olefin copolymer consisting of olefin and glycidyl ester of α,β-unsaturated acid, sodium stearate, barium stearate, sodium epoxy stearate,
Contains 0.1 to 5 parts by weight of at least one compound selected from the group consisting of barium epoxy stearate, monosodium monomethyl terephthalate, monosodium monomethyl isophthalate, and sodium salts of ethylene-α,β-unsaturated acid copolymers. A thermoplastic polyester composition for molding.